WHAT IS THERMIC FLUID?

A heat transfer fluid which absorbs heat from a source and transfers the heat in an indirect heating system

Two Basic Types:

Mineral Oil Based	Synthetic
Paraffins, Naphthenes	Aromatics, Toluene,    Diphenyl + Diphenyl Oxide

Mineral oil based Thermic fluids:

• Produced in a crude oil refinery
• Reasonably stable thermally at 260 C
• Mostly straight chain Hydrocarbons
• Most fluids blended with additives, like anti- oxidants and stabilizers
• Light coloured, transparent, feel like lubricants
• When heated, low boiling chemicals, volatile, moisture come out.
• These vaporize and get vented – normal for all fluids.
• Annual top-up: 5-10% of system holdup, depends on % of volatile & leakage in system.
• When overheated, carbonize
• When oxidized, acidic and viscous like grease

Synthetic Thermic fluids:

• ‘Synthesized’ from petrochemicals as thermic fluid
• Full temperature range covered by different fluids
• Mostly Benzene ring / cyclic compounds
• More stable thermally - long life, hence used in India for temperatures above 300 C
• Easily combine with oxygen and moisture, require Nitrogen blanket in expansion tank
• Some require pressurized expansion tank to remain in liquid phase
• Require negligible top-ups
• Very expensive in high temperature ranges
• Long life and almost zero top-ups can support high initial investment